This invention relates to a tape recorder whose microphone has its sensitivity made changeable in accordance with the object for which said tape recorder is applied.
A midget portable tape recorder is applied mainly for recording by a microphone. The condition under which recording is carried out by a microphone varies with circumstances. Where recording is undertaken with a microphone set apart from a sound source (hereinafter referred to as "off-mike recording"), for example, in a conference, then the microphone is preferred to have a high sensitivity. Where so-called dictation recording is carried out (hereinafter referred to as "on-mike recording"), then the microphone is desired to have a relatively low sensitivity. A tape recorder applied to the above-mentioned off-mike and on-mike recording is generally provided with an automatic level control (ALC) circuit such as an automatic gain control (AGC) unit or limiter. However, the level of an input to a microphone widely varies between, for example, comference recording (off-mike recording) and dictation recording (on-mike recording). Therefore, the ordinary simple low grade ALC circuit can not follow such noticeable variations in the level of an input to a microphone.
In other words, a tape recorder should be equipped with a sensitivity-changeable microphone in order to be suitably used not only for conference recording but also for dictation recording.
With the conventional portable tape recorder, a pause button for effecting a pause, and a switch for changing the sensitivity of a microphone are independently provided. Therefore, the outside of the known portable tape recorder has to be fitted with at least two switches for the pause mode and sensitivity-changing mode. This arrangement obstructs the miniaturization of an extremely small tape recorder such as a microcassette type. Further, an independent microphone sensitivity-changing switch should be shifted for each object of recording, thus involving troublesome work.